Magnetic sensor, method for manufacturing magnetic sensor, and current sensor

Abstract

A magnetic sensor includes: a magnetoresistive effect element having a sensitivity axis in a specific direction in which a fixed magnetic layer, a nonmagnetic material layer, and a free magnetic layer are laminated in this order; an antiferromagnetic layer which generates an exchange coupling bias with the free magnetic layer and which aligns the magnetization direction thereof in a predetermined direction provided on the free magnetic layer; and a ferromagnetic layer which generates an exchange coupling bias with the antiferromagnetic layer and which aligns the magnetization direction thereof in a predetermined direction provided on the antiferromagnetic layer. The magnetization direction on the exchange coupling bias in the free magnetic layer is the same direction as that on the exchange coupling bias in the ferromagnetic layer, and the ferromagnetic layer is able to impart a reflux magnetic field having a component along a sensitivity axis to the free magnetic layer.

What is claimed is: 
     
       1. A magnetic sensor, comprising:
 a magnetoresistive effect element having a sensitivity axis in a specific direction, the magnetoresistive effect element including: 
 a laminate structure in which a fixed magnetic layer and a free magnetic layer are laminated to each other with a nonmagnetic material layer provided therebetween, wherein 
 at a side of the free magnetic layer opposite to the side thereof facing the nonmagnetic material layer, an antiferromagnetic layer which generates an exchange coupling bias with the free magnetic layer and which aligns the magnetization direction of the free magnetic layer in a predetermined direction in a magnetization changeable state is provided, 
 at a side of the antiferromagnetic layer opposite to the side thereof facing the free magnetic layer, a ferromagnetic layer which generates an exchange coupling bias with the antiferromagnetic layer and which is able to align the magnetization direction thereof in a predetermined direction in a magnetization changeable state is provided, 
 the magnetization direction based on the exchange coupling bias generated in the free magnetic layer is the same direction as the magnetization direction based on the exchange coupling bias generated in the ferromagnetic layer, and 
 the ferromagnetic layer is able to impart a reflux magnetic field having a component in a direction along the sensitivity axis to the free magnetic layer. 
 
     
     
       2. The magnetic sensor according to  claim 1 ,
 wherein the magnitude of the exchange coupling bias generated in the ferromagnetic layer and the thickness thereof are set so as to reduce the component of a remnant magnetization of the free magnetic layer in the direction along the sensitivity axis. 
 
     
     
       3. A current sensor including the magnetic sensor according to  claim 2 , wherein the current sensor further includes a magnetic field detection bridge circuit and the current to be measured is measured by the difference in potential output from the magnetic field detection bridge circuit in accordance with an induction magnetic field. 
     
     
       4. The magnetic sensor according to  claim 1 ,
 wherein the antiferromagnetic layer is formed of IrMn. 
 
     
     
       5. A current sensor including the magnetic sensor according to  claim 4 , wherein the current sensor further includes a magnetic field detection bridge circuit and the current to be measured is measured by the difference in potential output from the magnetic field detection bridge circuit in accordance with an induction magnetic field. 
     
     
       6. The magnetic sensor according to  claim 1 ,
 wherein the fixed magnetic layer is a laminate in which a first magnetic layer and a second magnetic layer in contact with the nonmagnetic material layer are laminated to each other with a nonmagnetic interlayer provided therebetween, and the first magnetic layer and the second magnetic layer form a self-pinning structure in which the magnetizations thereof are fixed in antiparallel to each other. 
 
     
     
       7. A current sensor including the magnetic sensor according to  claim 6 , wherein the current sensor further includes a magnetic field detection bridge circuit and the current to be measured is measured by the difference in potential output from the magnetic field detection bridge circuit in accordance with an induction magnetic field. 
     
     
       8. The magnetic sensor according to  claim 1 ,
 wherein the magnitude of the exchange coupling bias generated in the ferromagnetic layer and the thickness thereof are set so as to reduce a high-temperature storage time dependence of the sensitivity of the free magnetic layer. 
 
     
     
       9. A current sensor including the magnetic sensor according to  claim 8 , wherein the current sensor further includes a magnetic field detection bridge circuit and the current to be measured is measured by the difference in potential output from the magnetic field detection bridge circuit in accordance with an induction magnetic field. 
     
     
       10. A current sensor including the magnetic sensor according to  claim 1 , wherein the current sensor further includes a magnetic field detection bridge circuit and the current to be measured is measured by the difference in potential output from the magnetic field detection bridge circuit in accordance with an induction magnetic field.